GF/src is now for 2.9, and the new sources are in src-3.0 - keep it this way until the release of GF 3

src-3.0/GF/Data/Parsers.hs

@@ -0,0 +1,196 @@
+----------------------------------------------------------------------
+-- |
+-- Module      : Parsers
+-- Maintainer  : Aarne Ranta
+-- Stability   : Almost Obsolete
+-- Portability : Haskell 98
+--
+-- > CVS $Date: 2005/04/21 16:22:06 $ 
+-- > CVS $Author: bringert $
+-- > CVS $Revision: 1.6 $
+--
+-- some parser combinators a la Wadler and Hutton.
+-- no longer used in many places in GF
+-- (only used in module "EBNF")
+-----------------------------------------------------------------------------
+
+module GF.Data.Parsers (-- * Main types and functions
+		Parser, parseResults, parseResultErr,
+		-- * Basic combinators (on any token type)
+		(...), (.>.), (|||), (+||), literal, (***),
+		succeed, fails, (+..), (..+), (<<<), (|>),
+		many, some, longestOfMany, longestOfSome,
+		closure,
+		-- * Specific combinators (for @Char@ token type)
+		pJunk, pJ, jL, pTList, pTJList, pElem,
+		(....), item, satisfy, literals, lits,
+		pParenth, pCommaList, pOptCommaList,
+		pArgList, pArgList2,
+		pIdent, pLetter, pDigit, pLetters,
+		pAlphanum, pAlphaPlusChar,
+		pQuotedString, pIntc
+	       ) where
+
+import GF.Data.Operations
+import Data.Char
+import Data.List
+
+
+infixr 2 |||, +||
+infixr 3 ***
+infixr 5 .>.
+infixr 5 ...
+infixr 5 ....
+infixr 5 +..
+infixr 5 ..+
+infixr 6 |>
+infixr 3 <<<
+
+
+type Parser a b = [a] -> [(b,[a])]
+
+parseResults :: Parser a b -> [a] -> [b]
+parseResults p s = [x | (x,r) <- p s, null r]
+
+parseResultErr :: Show a => Parser a b -> [a] -> Err b
+parseResultErr p s = case parseResults p s of
+  [x] -> return x
+  []  -> case 
+       maximumBy (\x y -> compare (length y) (length x)) (s:[r | (_,r) <- p s]) of
+    r -> Bad $ "\nno parse; reached" ++++ take 300 (show r)
+  _   -> Bad "ambiguous"
+
+(...) :: Parser a b -> Parser a c -> Parser a (b,c)
+(p ... q) s = [((x,y),r) | (x,t) <- p s, (y,r) <- q t]
+
+(.>.) :: Parser a b -> (b -> Parser a c) -> Parser a c
+(p .>. f) s = [(c,r) | (x,t) <- p s, (c,r) <- f x t]
+
+(|||) :: Parser a b -> Parser a b -> Parser a b
+(p ||| q) s = p s ++ q s
+
+(+||) :: Parser a b -> Parser a b -> Parser a b
+p1 +|| p2 = take 1 . (p1 ||| p2)
+
+literal :: (Eq a) => a -> Parser a a
+literal x (c:cs) = [(x,cs) | x == c]
+literal _ _ = []
+
+(***) :: Parser a b -> (b -> c) -> Parser a c
+(p *** f) s = [(f x,r) | (x,r) <- p s] 
+
+succeed :: b -> Parser a b
+succeed v s = [(v,s)]
+
+fails :: Parser a b
+fails s = []
+
+(+..) :: Parser a b -> Parser a c -> Parser a c
+p1 +.. p2 = p1 ... p2 *** snd
+
+(..+) :: Parser a b -> Parser a c -> Parser a b
+p1 ..+ p2 = p1 ... p2 *** fst
+
+(<<<) :: Parser a b -> c -> Parser a c  -- return
+p <<< v = p *** (\x -> v)
+
+(|>) :: Parser a b -> (b -> Bool) -> Parser a b
+p |> b = p .>. (\x -> if b x then succeed x else fails)
+
+many :: Parser a b -> Parser a [b]
+many p = (p ... many p *** uncurry (:)) +|| succeed []
+
+some :: Parser a b -> Parser a [b]
+some p = (p ... many p) *** uncurry (:)
+
+longestOfMany :: Parser a b -> Parser a [b]
+longestOfMany p = p .>. (\x -> longestOfMany p *** (x:)) +|| succeed []
+
+closure :: (b -> Parser a b) -> (b -> Parser a b)
+closure p v = p v .>. closure p ||| succeed v
+
+pJunk   :: Parser Char String
+pJunk = longestOfMany (satisfy (\x -> elem x "\n\t "))
+
+pJ :: Parser Char a -> Parser Char a
+pJ p = pJunk +.. p ..+ pJunk
+
+pTList  :: String -> Parser Char a -> Parser Char [a]
+pTList t p = p .... many (jL t +.. p) *** (\ (x,y) -> x:y) -- mod. AR 5/1/1999
+
+pTJList  :: String -> String -> Parser Char a -> Parser Char [a]
+pTJList t1 t2 p = p .... many (literals t1 +.. jL t2 +.. p) *** (uncurry (:))
+
+pElem   :: [String] -> Parser Char String
+pElem l = foldr (+||) fails (map literals l)
+
+(....) :: Parser Char b -> Parser Char c -> Parser Char (b,c)
+p1 .... p2 = p1 ... pJunk +.. p2
+
+item :: Parser a a
+item (c:cs) = [(c,cs)]
+item [] = []
+
+satisfy :: (a -> Bool) -> Parser a a
+satisfy b = item |> b
+
+literals :: (Eq a,Show a) => [a] -> Parser a [a]
+literals l = case l of 
+  []  -> succeed [] 
+  a:l -> literal a ... literals l *** (\ (x,y) -> x:y)
+
+lits :: (Eq a,Show a) => [a] -> Parser a [a]
+lits ts = literals ts
+
+jL :: String -> Parser Char String
+jL = pJ . lits
+
+pParenth :: Parser Char a -> Parser Char a
+pParenth p = literal '(' +.. pJunk +.. p ..+ pJunk ..+ literal ')'
+
+-- | p,...,p
+pCommaList :: Parser Char a -> Parser Char [a]
+pCommaList p = pTList "," (pJ p)                      
+
+-- | the same or nothing
+pOptCommaList :: Parser Char a -> Parser Char [a]
+pOptCommaList p = pCommaList p ||| succeed []            
+
+-- | (p,...,p), poss. empty
+pArgList :: Parser Char a -> Parser Char [a]
+pArgList p = pParenth (pCommaList p) ||| succeed [] 
+
+-- | min. 2 args
+pArgList2 :: Parser Char a -> Parser Char [a]
+pArgList2 p = pParenth (p ... jL "," +.. pCommaList p) *** uncurry (:) 
+
+longestOfSome :: Parser a b -> Parser a [b]
+longestOfSome p = (p ... longestOfMany p) *** (\ (x,y) -> x:y)
+
+pIdent :: Parser Char String
+pIdent = pLetter ... longestOfMany pAlphaPlusChar *** uncurry (:)
+  where alphaPlusChar c = isAlphaNum c || c=='_' || c=='\''
+
+pLetter, pDigit :: Parser Char Char
+pLetter = satisfy (`elem` (['A'..'Z'] ++ ['a'..'z'] ++ 
+                           ['\192' .. '\255'])) -- no such in Char
+pDigit  = satisfy isDigit
+
+pLetters :: Parser Char String
+pLetters = longestOfSome pLetter
+
+pAlphanum, pAlphaPlusChar :: Parser Char Char
+pAlphanum      = pDigit ||| pLetter
+pAlphaPlusChar = pAlphanum ||| satisfy (`elem` "_'")
+
+pQuotedString :: Parser Char String
+pQuotedString = literal '"' +.. pEndQuoted where
+ pEndQuoted =
+       literal '"' *** (const [])
+   +|| (literal '\\' +.. item .>. \ c -> pEndQuoted *** (c:))
+   +|| item .>. \ c -> pEndQuoted *** (c:)
+
+pIntc :: Parser Char Int
+pIntc = some (satisfy numb) *** read
+         where numb x = elem x ['0'..'9']
+